Prior art related to the present invention includes magnetic card readers, especially those with fluctuation in the sliding speed of the magnetic card relative to the magnetic head, for instance those in which the magnetic cards are manually moved. When magnetic stripes formed on magnetic cards are moved in sliding contact with magnetic heads to read or write information and the movement of the magnetic card is uneven, or too fast or too slow, errors occur and the reading or writing of information cannot properly take place with stability.
Since the magnetic card readers are much in use at banks and filling stations and are often used as media for direct cash transactions, accuracy and stability in the reading or writing of information by the magnetic card readers in whatever conditions of use are essential requirements. To properly exchange information between magnetic stripes on the magnetic cards and magnetic heads, it is desirable that, regardless of the moving speed of the magnetic card, information can be exchanged invariably at a specific density between the magnetic head and the magnetic stripe.